Geometric multigrid method for solving Poisson's equation on octree grids with irregular boundaries

Published: 6 February 2023| Version 2 | DOI: 10.17632/5y43rjdmxd.2


A method is presented to include irregular domain boundaries in a geometric multigrid solver. Dirichlet boundary conditions can be imposed on an irregular boundary defined by a level set function. Our implementation employs quadtree/octree grids with adaptive refinement, a cell-centered discretization and pointwise smoothing. Boundary locations are determined at a subgrid resolution by performing line searches. For grid blocks near the interface, custom operator stencils are stored that take the interface into account. For grid block away from boundaries, a standard second-order accurate discretization is used. The convergence properties, robustness and computational cost of the method are illustrated with several test cases.



Multigrid Method, Poisson Equation, Computational Physics